1. Field of the Invention
The present invention relates generally to systems and methods for preventing the unauthorized compression and recording of digitized music.
2. Description of the Related Art
The advantages of digitized video and music are numerous. One advantage is that digitized music can be compressed by a purchaser of the music, such that a person's entire music library can be stored on a single digital video disk (DVD). Another advantage of compressed music is that it can be conveniently stored in flash memory for subsequent decompression and playback by a portable music player that has no moving parts and that consequently can be made small for easy portability during activities such as jogging. Yet a further advantage of compressed music is that, being compressed, it is more quickly transmitted over media such as the Internet, compared to uncompressed music.
Unfortunately, however, pirates can take advantage of the last of the above-mentioned advantages to distribute the music over the Internet without the authorization of the copyright owner. In other words, pirates can take advantage of the ease by which compressed music can be distributed over the Internet to distribute the music without paying royalties to the copyright holder. Thus, while it is desirable to permit consumers to compress digitized music that has been properly paid for so that the consumers can use small players such as the one mentioned above, it is equally desirable that consumers cannot re-record music from pirate channels. The problem is not trivial to solve, because it is difficult to ascertain the difference between authorized, uncompressed music from CDs and unauthorized, decompressed music from the Internet.
One solution to the above-noted problem is to record a so-called “fragile” watermark in the prerecorded music on CDs. The fragile watermark, which is supposed to be inaudible but which sometimes is not, is machine-detectable in never-compressed music but gets destroyed by compression, and consequently is not present in subsequently decompressed music. Accordingly, an authorized compression device can determine whether music has the fragile watermark and if it doesn't, can refuse to compress the music.
As recognized herein, not only can the fragile watermark be detected by listeners, but it is also relatively easy to mimic by a hacker. Accordingly, the present invention makes the critical observation that a relatively more secure means is needed to prevent compression of music that has been received from an unauthorized compressed data stream, but to permit compression and subsequent re-recording of music obtained in an authorized transaction.